The effects of marihuana and derivatives or metabolites on intraocular pressure, outflow facility, blood flow and other measures of aqueous humor dynamics will be evaluated using in vivo and in vitro techniques. In vitro determinations on isolated rabbit ciliary processes will indicate whether a purely membrane effect of these compounds contributes to their ocular effects. In vivo studies will be made on the conscious and anesthetized rabbit as well as the sedated rhesus monkey. These studies will reveal the site and mode of action of cannabinoids in the eye through measurements of all the necessary parameters which control intraocular pressure. Measurements of intraocular pressure and total outflow facility will be made in the conscious rabbit and the effects of a series of cannabinoid drugs will be assessed. In the rhesus monkey many parameters can be determined with non-invasive techniques such that repeated control observations can be made on the same eye. Such a baseline will enable drug effects to be more readily evaluated. A glaucoma model will be made in monkey eyes for further evaluation of drugs, which prove efficacious on reducing intraocular pressure in normals, for their capability of lowering increased intraocular pressure.